[ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?)

  • From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
  • To: "IBIS Macro" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Mon, 30 Jun 2008 09:40:36 -0700

Walter,
 
I am not writing this to irritate you or anyone else,
this is purely informational for those who may not know.
 
The idea of "views" is already built into the VHDL-AMS
language.  The language is structured so that there is
an "entity" and inside the entity you can have multiple
"architectures".  The entity describes the equivalent
of a SPICE subcircuit definition, the ports (nodes) and
the generics (parameters) which may be the same for each
architecture (view).  The architecture contains the guts
of the subcircuit, and since we can have multiple architectures,
we can describe multiple views of the same thing.  For example,
an entity for a T-line could have multiple architectures:
 
Ideal, RLGC, S-parameter, Pole/Zero, ImpulseResponse, YouNameIt
 
Once there is a T-line entity in a library, all you need to
do is add more architectures as your knowledge increases...
 
In summary, VHDL-AMS already provides a netlisting syntax
(which I believe is easily translated to any SPICE netlist)
and it provides the multiple view syntax (entity/architecture).
 
This is another point why I feel that there is no need for us
to reinvent the wheel when it comes to designing our new EMD
specification.  It is already there, and I think this is 
actually pretty well done in VHDL-AMS...
 
Arpad
============================================================

________________________________

From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Walter Katz
Sent: Monday, June 30, 2008 10:29 AM
To: scott@xxxxxxxxxxxxx
Cc: IBIS Macro
Subject: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?)


Scott,
 
My EMD proposal includes a concept of "Views". One view might be as simple as a 
lumped RLC, other views would include distributed RLGC (lossy and lossless), as 
well as S-parameter and Pole-Zero. Each view would contain information about 
the nature of the model and its bandwidth. I would not exclude the ability to 
include proprietary models as well, as long as comparably accurate 
non-proprietary models were included as well. 
 
Walter
 
-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx 
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]On Behalf Of Scott McMorrow
Sent: Monday, June 30, 2008 11:08 AM
To: kumarchi@xxxxxxxxx
Cc: bob@xxxxxxxxxxxxx; wkatz@xxxxxxxxxx; IBIS Macro
Subject: [ibis-macro] Re: [!! SPAM] Re: EMD Pole-Zero Models (Why voltage 
controled sources?)
 
What IBIS would provide is the encapsulation and mapping to 
device/board/connector/cable pins in an EDA environment.  For example, several 
connector companies provide models of their connectors in the following form:

uncoupled spice
lossless coupled spice
S-parameter
Pole-zero

All of these could be provided as options in an EMD model, with the correct pin 
mapping.

There is currently no IBIS model type available for boards with components, 
coupled and lossy interconnect.

There is currently no IBIS model type available that can describe an actively 
equalized cable assembly.



Scott McMorrow
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax
 
http://www.teraspeed.com
 
Teraspeed® is the registered service mark of
Teraspeed Consulting Group LLC


C. Kumar wrote: 
before you go on to pole/zero approximation you should have an 'S' elements 
which directly provides the original s-parameter data either in time domain or 
freq domain. all the others like pole/zero are approximations, except in the 
case of circuit elements with analytic forms.

You can add to your list controlled sources with data provided multi 
dimensional tables; controlled elements with hysterisis; a generic expression 
controlled source of the form f(v,i, parameters)=0 and so on and so forth. It 
is possible to reduce the controlled sources to a finite set (order of 10;s)

however I am still with Arpad on this one here, unless I am not seeing 
something fundamental . These elements have been already implemented in 
equivalent forms in various flavors of spice and yes AMS and -A flavors. I fail 
to see how  IBIS 'inventing' its own form and convince vendors and users to 
adopt the yet another new/even improved  form.

--- On Mon, 6/30/08, Walter Katz <wkatz@xxxxxxxxxx> <mailto:wkatz@xxxxxxxxxx>  
wrote:
From: Walter Katz <wkatz@xxxxxxxxxx> <mailto:wkatz@xxxxxxxxxx> 
Subject: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled sources?)
To: bob@xxxxxxxxxxxxx
Cc: "IBIS Macro" <ibis-macro@xxxxxxxxxxxxx> <mailto:ibis-macro@xxxxxxxxxxxxx> 
Date: Monday, June 30, 2008, 12:54 AM
Bob,
 
Thanks for digging this up on the use of controlled voltage source for the
Laplace and Pole-Zero form of transfer functions.
 
Is the following a correct summary:
 
* A Touchstone file is a matrix of "Transfer Functions", where the
"Transfer
Function" is represented as a "Vector" of complex coefficients.
o Each element of the "Vector" is the amplitude of the "Transfer
Function"
at a specific
 frequency.
* Each of the "Transfer Functions" can be translated to Laplace form
with a
numerator and denominator polynomial.
o Hspice implements the Laplace form using the E and G LAPLACE controlled
voltage source.
* The numerator and denominator Laplace polynomials can be factored, the
numerator polynomial factored into a list of zeros, and the denominator
factored into a list of poles.
o Hspice implements the Pole-Zero form using the E and G POLE controlled
voltage source.
* Alternatively, each of "Transfer Functions" can be translated into
"Impulse Responses"
 
If this is correct, then Lossy RLGC, Touchstone, Laplace, Pole-Zero
interconnect blocks can simply be represented as an EMD "Block" of
the form:
 
EMD_Block_xxxx <list of nodes> len=<length> type=<type>
file=<file>
* Where
o EMD_Block_xxxx
* Instance Designator
o <list of nodes>
* List of
 nodes
o <length>
* Length of interconnect in meters (applies only to RLGC)
o <type>
* RLGC
* Touchstone
* Laplace
* Pole
* Impulse
o <file>
* RLGC
* Contains RLGC table data
* Touchstone
* sNp
* Laplace
* Contains Laplace polynomial coefficients
* Format needs specification
* Pole
* Contains Pole Zero data
* Format needs specification
* Impulse
* Contains Impulse Response data
* Format needs specification
 
It is a trivial exercise to convert any one of these "Types" of
EMD_Blocks
to Hspice W, S, E and G elements.
 
If all of the above is correct, then there is no need for EMD_Blocks that
are specifically voltage controlled sources.
 
 
To answer your question: An EMD models for a group of interconnect pins is
essentially an ICM [Nodal Path Description] where each of the N_sections is
essentially an EMD_Block. The [Nodal Path Description]
 becomes a subckt with
nodes consisting of external EMD pins and IBIS component pins. In ICM all of
the N_section can either be all RLGC or all Touchstone. In EMD the
EMD_Blocks can be any combination of RLGC, Touchstone, Laplace, Pole,
Impulse, Resistor, Capacitor, Inductor, Conductance or K (coupling)
elements.
 
Walter
 
-----Original Message-----
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]On Behalf Of Bob Ross
Sent: Sunday, June 29, 2008 10:53 PM
To: wkatz@xxxxxxxxxx
Cc: IBIS Macro
Subject: [ibis-macro] Re: EMD Pole-Zero Models (Why voltage controled
sources?)
 
Walter:
 
Here are some responses to your questions
 
1.  HSPICE and some other SPICEs implement the Laplace and pole-zero
     elements as a network function WITHIN controlled sources including
     the VCVS (E) and VCCS (G) elements.  The documention is hard to
     find, but the HSPICE
 syntax is in the HSPICE Applications Manual:
 
     Exxx n+ n- LAPLACE in+ in-  k0 k1 ... kn / b0 b1 ... bm
     Gxxx n+ n- LAPLACE in+ in-  k0 k1 ... kn / b0 b1 ... bm
 
     Exxx n+ n- POLE in+ in-  a {cmpl zeros) / b (cmpl poles}
     Gxxx n+ n- POLE in+ in-  a {cmpl zeros) / b (cmpl poles}
 
2.  I think of a pole-zero block, not as the single Laplace transfer
     element, but as an n-port block such as proposed in some private
     Touchstone-like formats and possibly implemented internally
     and automatically from n-port table data.
 
My question:
 
     When you say interconnect block modules of Resistor/Inductor/
     Capacitor, do you really mean a low-level SPICE or SPICE-like
     syntax within "SPICE" subcircuits for interconnect structures?
 
     That is where K and controlled sources are valuable for many
     reasons.  While we have not really discussed this, I have been
    
 assuming that we need such low-level capability for EMD.  We
     could formally add a basic SPICE-syntax subcircuit to the list
     below as one of the modules with its internal SPICE-like netlist
     used for connecting the R/L/C/K/E/F/G/H ... elements.
 
Bob
 
Walter Katz wrote:
 > All,
 >
 >
 >
 > Based on the following assumptions for an EMD:
 >
 >
 >
 >     * A module as a netlist of IBIS components and external pins
 >     * Interconnect models between these IBIS component pins consist of a
 >       netlist of interconnect blocks
 >     * Interconnect block models are:
 >           o Resistors
 >           o Inductors
 >           o Capacitors
 >           o Distributed RLGC models
 >           o S parameter Models
 >           o Impulse Response Models
 >           o Pole-Zero Models
 >
 >
 
 >
 > The purpose of this e-mail is to raise the issue of what is a Pole-Zero
 > model and why do we need voltage controlled sources.
 >
 >
 >
 > I refer to http://www.ece.uci.edu/docs/hspice/hspice_2001_2-217.html
 >
 >
 >
 >
 >     Understanding Pole/Zero Analysis
 >
 > In pole/zero analysis, a network is described by its network transfer
 > function which, for any linear time-invariant network, can be written in
 > the general form:
 >
 >
 >
 > In the factorized form, the general function is:
 >
 >
 >
 > It seems to me that a Pole-Zero model can either be represented as a set
 > of numbers like the polynomial coefficients a0, b0, a1, b1, a2, b2, ..
 > or the factorized form a0, b0, z1, p1, z2, p2, ?
 >
 > Where is the controlled voltage source?
 >
 > I assume that one can model
 the pole-zero form into Spice, Verilog, and
 > VHDL primitives, and doing so might utilize controlled voltage sources
 > and other simulator specific models.
 >
 > Why it is not sufficient to just have a Pole-Zero model (either with
 > polynomial coefficients and/or pole-zero coefficients).
 >
 > Walter
 >
 
 
--
Bob Ross
Teraspeed Consulting Group LLC     Teraspeed Labs
121 North River Drive              13610 SW Harness Lane
Narragansett, RI 02882             Beaverton, OR 97008
401-284-1827                       503-430-1065
http://www.teraspeed.com           503-246-8048 Direct
bob@xxxxxxxxxxxxx
 
Teraspeed is a registered service mark of Teraspeed Consulting Group LLC
 
 
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